Catheter Delivery System For Stent Valve

ABSTRACT

A delivery catheter for a stent. The delivery catheter may comprise a distal end and a proximal end. The distal end includes a stent attachment region adapted to receive a stent. The stent may be of the self-expanding type. The catheter further comprises a handle at its proximal end and at least one sheath which may at least partially circumferentially cover said stent such as to retain it in a collapsed configuration. The sheath is coupled at its proximal end to an actuator located on said handle portion.

FIELD OF THE INVENTION

The present invention relates to catheter delivery systems for stentvalves according to the independent claims.

BACKGROUND TO THE INVENTION

Conventional approaches for cardiac valve replacement require thecutting of a relatively large opening in the patient's sternum(“sternotomy”) or thoracic cavity (“thoracotomy”) in order to allow thesurgeon to access the patient's heart. Additionally, these approachesrequire arrest of the patient's heart and a cardiopulmonary bypass(i.e., use of a heart-lung bypass machine to oxygenate and circulate thepatient's blood). In recent years, efforts have been made to establish aless invasive transcatheter cardiac valve replacement procedure, viaeither a transvascular approach, i.e. delivering the new valve throughthe femoral artery, or by transapical route, where the replacement valveis delivered between ribs and directly through the wall of the heart tothe implantation site.

Valve stents for use within a human body usually comprise a valvecomponent and a stent component. The stent component is configured tohouse at least a portion of the valve component. According to some knownproposals (see e.g. WO 2009/053497), the stent component furtherincludes a lower anchoring crown comprising an at least partly conicalbody, the lower anchoring crown defining the proximal end of the stentcomponent. The stent component further comprises an upper anchoringcrown in communication with the lower anchoring crown and comprising anat least partly conical body, whereby the conical body of the loweranchoring crown slopes outwardly in the direction of the proximal end,and the conical body of the upper anchoring crown slopes outwardly inthe direction of the distal end. A conical or cylindrical commissuralpost section is located distally of the distal end of the upperanchoring crown. Further distally, a stabilization arch section iscomprised.

While less invasive and arguably less complicated, percutaneous heartvalve replacement therapies (PHVT) still have various shortcomings,including ease of use of a delivery system for the replacement valve,which can directly influence the inability for a surgeon to ensureproper positioning and stability of the replacement valve within thepatient's body. Specifically, if the replacement valve is not placed inthe proper position relative to the implantation site, it can lead topoor functioning of the valve. For example, in an aortic valvereplacement, if the replacement valve is placed too high, it can lead tovalve regurgitation, instability, valve prolapse and/or coronaryocclusion. If the valve is placed too low, it can also lead toregurgitation and mitral valve interaction.

SUMMARY OF THE INVENTION

It may be desirable to provide a catheter delivery device for stentvalves avoiding the shortcoming known in the art and specifically toprovide a delivery catheter system allowing for a simple and effectiveuse, to facilitate accurate positioning and deployment of a stent valve.Some of the following description refers generally to a stent while someembodiments illustrate a stent in the form of a stent-valve. Referencesto a stent may be read optionally as referring to a stent-valve, andvice-versa.

Broadly speaking, one aspect of the invention provides a deliverycatheter for a stent. The delivery catheter may comprise a distal endand a proximal end. The distal end includes a stent attachment regionadapted to receive a stent. The stent may be of the self-expanding type.The catheter further comprises a handle (also referred to as handleportion) at its proximal end and at least one sheath which may at leastpartially circumferentially cover said stent such as to retain it in acollapsed configuration. The sheath is coupled at its proximal end to anactuator located on said handle portion. The delivery catheter mayfurther comprise one, or any combination of two or more, of thefollowing features (which are all optional):

(i) The actuator may comprise a manual rotary control (also referred toherein as a rotary handle part) arranged such as to move the sheath inthe distal and/or proximal direction(s) in response to rotation thereof.The actuator may comprise a single rotary control. Optionally, therotary control is coaxial with, and/or configured to rotate around, alongitudinal axis of the catheter.

In some embodiments, the single rotary control is configured to drivetranslation (e.g. linear translation) of the sheath over a fulloperative range of movement of the sheath.

In some embodiments, the actuator is configured to drive translation ofthe sheath from a (e.g. fully) closed position to a (e.g. fully) openposition by three complete turns or less of the rotary control,optionally two complete turns or less (measured in quarter turns, e.g.,¼ turn, ½ turn, complete turn, etc.). The translation of the sheath maybe at least 50 mm, or at least 60 mm, or at least 70 mm. Such arelatively large translation of the sheath for relatively few turns ofthe rotary control may involve a relatively coarse thread pitch of athreaded element for converting the rotary movement into lineartranslational movement. The delivery catheter may optionally comprise afriction member for resisting rotation of the rotary control. Thefriction member may comprise a protuberance or member carried on atleast one of confronting surfaces of a handle housing and the rotarycontrol. For example, the friction member may be provided on an outersurface of the handle housing, and/or an inner surface of the rotarycontrol. Such positioning can provide a relatively largefriction-generating contact area, facilitate ease of construction andprovide predictable control of the amount of friction generated. In someembodiments, the friction member comprises an O-ring, for example, ofelastomeric material.

In some embodiments, the rotary control has an elongate shape (e.g. itsaxial length is longer than its diameter, for example at least twice aslarge).

In some embodiments, the rotary control has an axial length of at least3 cm, or at least 4 cm, or at least 5 cm, or at least 6 cm, or at least7 cm, or at least 8 cm, or at least 9 cm, or at least 10 cm. Such sizescan facilitate intuitive gripping in the hand, for example, cupping therotary control with the fingers and/or palm. The outer shape of therotary control may be generally cylindrical and/or generally drum-like.

(ii) The rotary control may be configured to translate linearly withrespect to a handle housing as the rotary control is rotated. Suchtranslation progressively exposes indicia on the housing and/or control,the indicia indicating an extent of displacement of the sheath at thedistal end. Such an arrangement provides an operator with an importantindication of the state of the distal end of the delivery catheter. Asurgeon may use this indication (optionally in combination withlive-imaging of the implantation site, such as live x-ray imaging) tobetter monitor and control the stent implantation procedure.

In some embodiments, the rotary control may translate linearly in unisonwith translation of the sheath. The indicia may be a full-scale (e.g.life size) representation of the position or state of the sheath at thedistal end.

In some embodiments, indicia on the handle are repeated, to be presentedat least two different positions around the circumference of the handle,or at least three such different positions, or at least four differentsuch positions. This may permit the indicia to be easily visibleindependently of a rotational orientation of the handle. Alternatively,the indicia may comprise one or more annular closed and/or splitring-shaped markings visible from substantially any orientation of thehandle.

(iii) Additionally or alternatively, the stent carried by the deliverycatheter comprises a first portion and a second portion intended to bedeployed in respective first and second distinct deployment phases. Forexample, the first and second portions may be intended to fit onopposite sides of the annulus of an existing (e.g., native) valve. Thefirst portion may be supra-annular and the second portion may besub-annular. Additionally or alternatively, the first and secondportions may comprise opposed crowns and/or oppositely divergentportions.

In some embodiments, the handle of the delivery catheter comprisesindicia associated with movement of the actuator, for indicating atleast one limit position associated the first and/or second deploymentphases. A surgeon may use this indication (optionally in combinationwith live-imaging of the implantation site, such as live x-ray imaging)better to monitor and control the stent implantation procedure. Inparticular, the surgeon may, by checking the indicia, know how close thedelivery catheter is to reaching the end of a respective deploymentphase. Such information may be less evident from live imaging alone.This may enable the surgeon better to adapt the speed of deployment.

In some embodiments, indicia on the handle are repeated, to be presentedat least two different positions around the circumference of the handle,or at least three such different positions, or at least four differentsuch positions. This may permit the indicia to be easily visibleindependently of a rotational orientation of the handle. Alternatively,the indicia may comprise one or more annular closed and/or splitring-shaped markings visible from substantially any orientation of thehandle.

(iv) The handle may have a profile including a bulbous, e.g rounded,portion providing a tactile positioning guide for an operator's hand.The handle may optionally comprise a single bulbous portion.

The rounded bulbous portion may have a radial height, compared to atleast one adjacent surface of the handle, of at least 5 mm, at least 6mm, at least 7 mm, or at least 8 mm. The rounded bulbous portion mayhave an axial extent of any of: at least 20 mm; at least 25 mm; at least30 mm. Additionally or alternatively to any of the above, the roundedbulbous portion may have an axial extent of: not greater than 40 mm; notgreater than 30 mm; not greater than 35 mm.

The rounded portion may have a part-spherical and/or frusto-sphericalshape. The rounded portion may have a radius of curvature of any of: atleast 15 mm; at least 20 mm; at least 23 mm. Additionally oralternatively to any of the above, the radius of curvature mayoptionally be: not greater than 60 mm; not greater than 50 mm; notgreater than 40 mm; not greater than 30 mm; not greater than 25 mm; notgreater than 23 mm.

Such arrangements can provide a highly intuitive and versatile tactilepositioning guide for the handle. The guide may fit snugly in the palmof the hand, and/or be cupped comfortably by the fingers. The guide mayalso provide a suitable surface for gripping with the fingers to applyaxial force to the handle. The guide may also provide substantially thesame feel to the operator whatever the rotational orientation of thehandle around the catheter axis.

In some embodiments, the actuator may be distinct from the roundedbulbous portion.

The rounded bulbous portion may be an integral part of the handle and/ora housing forming at least a portion of the handle.

(v) In some embodiments, the handle may be generally radiallysymmetrical. For example, the handle may be absent any cantilever handlegrips. This may enable the delivery catheter to be versatile for usewith any rotational orientation about the catheter axis, without theorientation making the handle more awkward to hold, manipulate orobserve. This may be especially advantageous where the stent has anon-predetermined rotational orientation with respect to the deliverycatheter and/or where the delivery catheter may need to be rotated aboutits longitudinal axis for aligning the stent with respect to the nativeanatomy. For example, the handle may have a generally roundcross-section profile.

In some embodiments, indicia on the handle are repeated, to be presentedat least two different positions around the circumference of the handle,or at least three such different positions, or at least four differentsuch positions. This may permit the indicia to be easily visibleindependently of a rotational orientation of the handle. Alternatively,the indicia may comprise one or more annular closed and/or splitring-shaped markings visible from substantially any orientation of thehandle.

(vi) The handle may further comprise at least one indicator rotatableabout a catheter axis. The indicator may be positionable to indicate arotational alignment of a stent (e.g., stent-valve) with respect to thehandle. The indicator may be manually positionable.

This aspect of the invention may enable the operator to set a convenientindication of the rotational alignment of the stent. In someembodiments, the rotational orientation of the stent may be variable ornon-predetermined with respect to the delivery catheter. For example,the stent may have a variable or non-predetermined orientation withrespect to a stent holder of the attachment region. Additionally oralternatively, the stent holder may have a non-predetermined orientationwith respect to the handle. However, although the orientation may benon-predetermined, it may be unlikely to change after loading of thestent into the delivery catheter. The orientation may be visible duringand/or following loading, allowing the indicator to be set accordinglyto provide an indication useful for the implantation procedure. Once thedistal end has been inserted into the body, the distal end (and thestent) is no longer directly visible. The operator may have access tolive imaging (e.g. x-ray imaging) from which the rotational orientationmay be deduced. However, the provision of an indicator directly at thehandle can provide a direct and intuitive indication of the orientationto further assist the operator, and remove any ambiguity from the x-rayimaging.

In some embodiments, the stent is a valve stent (also referred to as astent-valve) comprising a valve having valve leaflets meeting at, and/orsupported at, a plurality of peripheral commissures. The indicator maycomprise indicia for indicating the rotational orienation of thecommissures. The indicator may comprise plural indicia, e.g. one foreach commissure.

The indicator may comprise a rotatable collar mounted towards a distalend of the handle. The rotatable collar may bear indicia (e.g. laserinscribed indicia, or indicia members embedded at least partly withinthe collar).

(vii) The delivery catheter may further comprise a stem portionextending between the handle and the distal portion. The stem portionmay have a flexure characteristic such that, in order to produce flexuredisplacement of 10 mm using a three-point bending test, the appliedforce is between 2.5 and 7.5 N (inclusive range). The three-pointbending test may comprise supporting the stem portion at two spacedapart positions, and observing the degree of bending displacement (e.g.,with respect to a straight axis) when a force is applied, in adiametrically opposed direction to the supports, at a position midwaybetween the spaced apart support positions. The test may be carried outat room temperature.

Optionally, the defined range of applied force may be associated with aspacing between the supports that is between about 16 and about 20 timesthe outer diameter of the stem.

In one example, the spacing between the supports may be 20 times theouter diameter of the stem. The applied force may be between 2.5 and 4.5N. Optionally the applied force may be at least 2.6N, optionally atleast 2.7N, optionally at least 2.8N, optionally at least 2.9N,optionally at least 3.0N, optionally at least 3.1N, optionally at least3.2N, optionally at least 3.3N, optionally at least 3.4N, optionally atleast 3.5N, optionally at least 3.6N, optionally at least 3.7N,optionally at least 3.8N, optionally at least 3.9N, optionally at least4.0N. Additionally or alternatively to any of the above, the appliedforce may optionally be no greater than 4.0N, optionally no greater than3.9N, optionally no greater than 3.8N, optionally no greater than 3.7N,optionally no greater than 3.6N, optionally no greater than 3.5N,optionally no greater than 3.4N, optionally no greater than 3.3N,optionally no greater than 3.2N, optionally no greater than 3.1N.Optionally, the applied force may be between about 3.0N and about 3.7N

In another example, it may not be practical to using a spacing of 20times the outer diameter of the stem if (for example), the stem as usedin the delivery device is shorter than would be needed for suchmeasurement. For example, the outer diameter may be about 9.8 mm (+−0.5mm), and the available length for measurement may be about 160 mm. Inthat case, the ratio of the distance (spacing) divided by the outerdiameter is about 16. For such an example (spacing 160 mm and/or outerdiameter of 9.8 mm (+−0.5 mm) and/or a spacing of about 16 times theouter diameter, the applied force may be between about 6.0 and about7.5N. Optionally, the applied force may be at least 6.1N, optionally atleast 6.2N, optionally at least 6.3N, optionally at least 6.4N,optionally at least 6.5N, optionally at least 6.6N, optionally at least6.7N, optionally at least 6.8N, optionally at least 6.9N, optionally atleast 7.0N, optionally at least 7.1 N, optionally at least 7.2N,optionally at least 7.3N, optionally at least 7.4N. Additionally oralternatively to any of the above, the applied force may optionally beno greater than 7.4N, optionally no greater than 7.3N, optionally nogreater than 7.2N, optionally no greater than 7.1N, optionally nogreater than 7.0N, optionally no greater than 6.9N, optionally nogreater than 6.8N, optionally no greater than 6.7N, optionally nogreater than 6.6N, optionally no greater than 6.5N, optionally nogreater than 6.4N, optionally no greater than 6.3N, optionally nogreater than 6.2N, optionally no greater than 6.1 N. Optionally, theapplied force may be between about 6.5 and about 7.0N

Such flexure characteristics may be advantageous in meeting theconflicting desirata of flexibility and support. Especially in the caseof a transapical approach, the delivery catheter has to providesufficient support to be able to advance the distal end through arelatively tight access aperture in the ventricle wall. It is desirablethat the aperture in the ventricle be as small as possible, to reducerisk of interference with the distribution of natural electrical pulsesessential to healthy heart operation, and/or reduce the invasiveness ofthe procedure on the heart tissue, and/or facilitate easier closingafter the procedure to restore the integrity of the ventricle wall,and/or facilitate the patient's recovery after the procedure. It isdesirable to create the access aperture undersized, and rely on theelasticity of the heart muscle tissue to allow the aperture to expandelastically to accommodate passage of the delivery cathetertherethrough. Such a tight fit can also provide a self-seal againstblood leakage, the procedure being carried out while the heart remainsbeating to pump blood around the circulatory system. However, thedelivery catheter has to support application of force from the proximalend to drive the distal portion through such an undersized aperture. Thedelivery catheter also has to be flexible to accommodate a non-straightdelivery path through the heart and the existing valve. Additionally,different surgeons have different preferences for the entry path throughthe anatomy to the heart. For example some surgeons prefer a relativelyflat entry along a direction close to the patients body, while othersprefer a more inclined path. A stiff catheter can provide excellentsupport, but without flexibility the catheter may not accommodate thenon-straight delivery path, but may be difficult to introduce andposition, and may not achieve optimum positioning of the prostheticvalve. The flexure characteristic defined herein can provide asurprisingly good balance between the two.

The three point bending test parameter as defined above is used because,in the some embodiments, the stem portion comprises plural tubes nestedone within the other, with or without a substantial clearancetherebetween. A small flexure might only involve flexing of one tube.The above parameter can provide a consistent parameter applicable to theentire stem portion instead of only a single tube.

(viii) In some embodiments, the distal end is intended to be insertedinto a human body, such as into the heart and/or circulatory system. Theproximal end is intended to stay outside of the patient and to allowmanipulation of the catheter by an operator, e.g. a surgeon. The distaland the proximal end are thereby connected by a stem or trunk portion,comprising at least one tubular member.

As understood herein, the terms “distal” and “proximal” define theorientation of an element from the operator of the delivery device.Therefore, the “proximal end” is the end of the catheter device which isnearer to the operator, while the “distal end” is farther away.

At the distal end, the catheter delivery system includes a stentattachment region. In some embodiments, the stent attachment regioncomprises retaining means such as to retain the stent on the catheter ata defined longitudinal position. This allows the user to advance thecatheter through a portion of the heart of a patient, e.g. through aventricle, or through the vasculature of a patient, e.g. through theaorta, without the danger that the stent might slip off the catheter. Insome embodiments, the retaining means are thereby configured in such away as to release the stent during or just after its expansion.

The stent used in connection with the catheter delivery system accordingto the present invention may be of the self-expanding type. Such stentsare known in the art and are made of or comprise a superelastic materialsuch as a Nickel-Titanium alloy, e.g. available under the name Nitinol.Alternatively the stent might also be made of or comprise other metallicmaterials, such as metallic materials exhibiting some elasticity.Further alternatively, the stent might also be deployable by means of aballoon or the like.

The catheter delivery device further comprises a handle portion locatedat its proximal end. The handle portion provides means for an operatorto hold and operate the catheter delivery system. These may includehandles, knobs, buttons, trigger elements, etc.

Further, the delivery device comprises at least one sheath. Said sheathmay at least partially circumferentially cover the stent. By coveringthe stent, the sheath holds the stent in a collapsed configuration, suchthat the stent may be introduced into the circulatory system. In someembodiments, the sheath completely covers the stent during insertion.Once the stent is positioned at the right place, e.g. over the aorticvalve, the sheath may be moved proximally over the stent, therebysequentially uncovering the stent. The portions of the stent which areuncovered are thereby free to expand.

For this purpose, the sheath is coupled to an actuator located on saidhandle. The coupling thereby is either direct or indirect, depending onthe kind of actuator used. Especially in the case where the actuatorcomprises a rotational movement, an element transforming said rotationalmovement into a translational movement may be arranged between thesheath and the actuator. The element may, for example, be threaded. Thethread may be helical.

In some embodiments, the actuator in the catheter delivery systemaccording to the present invention consists of a single rotary handle orhandle part. This handle (part) is thereby arranged in such a way as tomove the sheath either in the distal or in the proximal direction. Insome embodiments, the rotary handle (part) is configured in such a wayas to move the sheath both in the distal and in the proximal direction,for example, depending on the direction of rotation of the actuator.This offers the advantage that the sheath may not only be moved over thestent along the proximal direction thereby releasing the stent, but alsoalong the distal direction thereby re-capturing the stent and/orfacilitating loading of the stent into the delivery catheter. In someembodiments, it may be possible to revert certain expanded portions ofthe stent into the collapsed configuration. This may allow repositioningof a stent if needed.

The rotary handle (part) may be configured in any suitable way. In someembodiments, the rotary handle (part) is in the form of a cylinderarranged at the proximal end of the handle. Alternatively, the rotaryhandle may also be configured as knob or crank.

(ix) The delivery catheter includes gear means providing for at leasttwo different transmission or gear ratios between the movement ofactuation means and the movement of the sheath, depending on theposition of the distal end of the sheath along the stent and/or withrespect to the attachment region.

The gear means allow for at least two different gear ratios between themovement of the actuation means and the movement of the sheath. The gearratio thereby is the proportion between the distance that the distal endof the sheath is moved in comparison to the distance that the actuationmeans has been moved. For example, in the case of a rotary handle, aconstant gear ratio would mean that for every turn of the handle thedistal end of the sheath would move along the same distance. As soon asa gear means with at least two different gear ratios depending on theposition of the distal end of the sheath along the stent is used, thedistal end of the sheath moves a certain first distance for every turnof the handle with the first gear ratio and a second distance differentfrom the first distance for every turn of the handle with the secondgear ratio. The second distance may be bigger or smaller than the firstdistance.

A low gear ratio means that the distal end of the sheath will move ashorter distance along the stent compared to the movement of theactuation means. Taking a rotary handle as an example, this means thatthe distance which the distal end of the sheath moves for every turn ofthe handle will be shorter than with a higher gear ratio.

Such a configuration allows providing a catheter delivery system havingdifferent unsheathing characteristics depending on which portion thedistal end of the sheath is being moved. Specifically, the deliverydevice can be configured such that a small gearing ratio is providedwhen the distal end of the sheath is moving along portions of the stentrequiring slower and/or more accurate deployment.

The gear means also provides a kind of feedback mechanism to theoperator. The force needed to move the sheath will be higher with a highgear ratio compared to a low gear ratio. In the case of a rotary handle,this translates into a higher torque to be applied to the handle. Thiscan readily be sensed by an operator or alternatively be measured by aninstrument.

In some embodiments, the catheter delivery device according to thepresent invention comprises a single rotary handle as actuation means,whereby said rotary handle is arranged such as to move the sheath bothin the distal and the proximal direction, wherein a gear means isarranged between said rotary handle and the proximal end of said sheath.

Alternatively, the actuation means may also comprise a trigger elementmoveable in the distal and the proximal direction. The trigger elementis thereby configured such as to move the sheath element in the distaland/or the proximal direction, wherein a gear means is arranged betweenthe proximal end of the sheath and the trigger element.

In some embodiments, said gear means is configured such that when thesheath is moved in the proximal direction to unsheath the stent, thegearing means provides a different gear ratio, such as a higher gearratio when the sheath moves along a first portion of the stent comparedto the gear ratio provided when it moves along a second portion of thestent located proximally to said first portion.

When used in combination with a valve stent intended for trans-apicalinsertion, this means that unsheathing and hence deployment of thedistal part of the stent located in the aorta will take place with ahigh gear ratio. Especially but not exclusively in the case that themost distal parts usually do not serve to anchor the stent but rathercomprise stabilizing means, the operator needs a less precise control ofthe deployment. Further, a high gear ratio enables a quicker deploymentas compared with a lower gear ratio. The more proximal portions of thestent may comprise one or more anchoring crowns. Especially but notexclusively in the case that it is important to have a correct placementand orientation of the stent when deploying the anchoring crown orcrowns, it is advantageous to use a low gear ratio, as this enables theoperator to have a more accurate control on the deployment. Further, thedeployment speed will also be lower, thereby reducing the risk of missorientation of the crown. As the force needed to move the sheath is alsolower when using a lower gear ratio, re-capture of the stent may beeasier.

In some embodiments, said gear means is further configured such that thegear ratio provided when the sheath moves along said second portion ofthe stent is different (e.g., lower), compared to the gear ratioprovided when the sheath moves along a third portion of the stentlocated proximally to said second portion.

In some embodiments, the most proximal portion of the stent comprisesattachment elements adapted to be coupled to the retaining means locatedon the catheter. The coupling may be configured in such a way as toprovide for a de-coupling of the stent as soon as its most proximalportion expands. This may e.g. be achieved by providing loops on themost proximal portion of the stent which are mounted on pins provided onthe catheter. As long as the stent is held in its collapsedconfiguration, the pins remain within the loops, thereby realisablycoupling the stent to the catheter. As soon as the stent expands, theloops will slip over the pins thereby uncoupling the stent from thecatheter. Alternatively, any other suitable coupling means may be used.

As it is favourable that all coupling means are decoupled simultaneouslysuch as to not lead to a miss orientation of the stent, it is desirablethat the distal end of the sheath may be moved quicker along the mostproximal portion of the stent than along the foregoing portions. This isachieved by providing a higher gear ratio.

In some embodiments, the gear means comprises a cylindrical threadedelement having at least two regions with a different thread pitch.

The thread pitch is the distance along the longitudinal axis between twocrests of the thread. As the threaded element according to the presentinvention has a single thread, the pitch corresponds to the lead.Therefore the pitch may also be defined as the advancement of the sheathfor each turn of the threaded element.

Providing a gear means with a cylindrical threaded element provides fora simple and easy to use catheter delivery device. In one embodiment,the cylindrical threaded element may be provided within the handle andmay be directly coupled to the actuation means provided as rotaryhandle. On the inside of the handle, a pin may be provided which engagesthe thread. In an alternative embodiment, the thread may be provided onthe inner side of a rotary actuation means provided as hollow cylinder.The sheath is thereby coupled to a pin which engages the thread.Further, any other suitable configuration may be used.

The thread may be provided with any suitable profile. In someembodiments, the thread has a rectangular or rounded profile.Alternatively, the thread may also comprise a triangular profile.

The pin which is engaged into the thread may comprise a rolling ball atits tip, thereby reducing the friction force between the pin and thethread.

The threaded element comprises a thread with a greater pitch in a firstregion compared to the pitch in a second region, said greater pitchallowing a greater gear ratio when the sheath moves along the firstportion than along the second portion of the stent.

In a further embodiment, the threaded element comprises a thread with agreater pitch in a third region compared to the pitch in the secondregion, said greater pitch allowing a greater gear ratio when the sheathmoves along the third portion of the stent than over the second portion.

This allows providing a catheter delivery system with a gear meanscomprising different gear ratios.

Further, alternatively, the gear means is configured such that differentgear ratios are provided when the sheath moves along the second portionof the stent, such as by providing a varying pitch on the second regionof the threaded element.

This provides for different sensitivities and/or unsheathing speeds whendeploying the central portions of a stent. E.g. the gear ratio may bevaried for deployment of the upper and/or the lower crown of the stent.

In some embodiments, the cylindrical threaded element is exchangeable.As such, it is possible to easily vary the combination of gear ratios,and especially to provide specific combinations for different stentapplication methods and/or stent sizes.

(x) The catheter comprises feedback or braking means (e.g., tactilefeedback means) to indicate when the distal end of the sheath hasreached a defined position on the stent during proximal and/or distalmovement of said sheath along said stent or to cause a braking effectwhen the distal end of the sheath has moved beyond a certain positionalong the stent.

The feedback means may be tactile means. This allows the operator tosense when the distal end of the sheath has reached a defined position.As the feedback means have a direct influence on the movement theoperator uses to deploy the stent, the feedback will be more direct thanif other feedback means, such a light or sound signal were used.Advantageously, the feedback means warn the operator that the distal endof the sheath is about to move over the proximal end of the stent.

Alternatively, a catheter delivery device according to the presentinvention may comprise more than one feedback and/or braking means, suchas two, three or more defining various predetermined intermediatepositions.

In one embodiment, said feedback means comprise at least one removablepin or stop limiting the movement of said distal end of the sheathbeyond a certain position on the stent. Once the distal end of thesheath reaches the defined position, no further movement will bepossible until the stop is removed. Alternatively, an element may beprovided which does not completely stop the movement, but which may bepushed out, e.g., against the force of a spring. As the removal of thepin or stop by moving the actuation means further will require someadditional force, the operator will have a tactile feedback.

In an alternative embodiment, the feedback means may be formed as abraking means comprising an element applying an additional resistance tothe actuation means once the distal end of the sheath moves beyond acertain point on the stent. This may be achieved by means of additionalfriction forces acting on the actuation means or the sheath. Theresistance may alternatively also be applied by a gear means.

Further, alternatively, the feedback or braking means may comprise athreaded element with a varying thread pitch, wherein a decrease of saidthread pitch increases the resistance of the actuation means. Such afeedback or braking means is especially advantageous on catheterdelivery devices where the actuation means consist of a trigger element.

Said feedback means may be arranged such as to avoid movement of thesheath beyond a position on said stent beyond which an increased risk ofunwanted self-deployment of the stent exists.

Once the distal end of the sheath is near the proximal end of the stent,there is a certain risk that the stent pushes itself out of the sheathby means of the expansion force. This may lead to an unwanted release ofthe stent before it is correctly oriented and placed. To avoid such apremature release, the movement of the distal end of the sheath beyond acertain point where this risk exists may be stopped or slowed down bythe feedback or braking means.

Broadly speaking, a further independent aspect of the invention relatesto a stop that is removably engageable with a delivery catheter forblocking or resisting deployment movement of a portion of the catheterfor deploying a stent therefrom, at least beyond a predetermineddeployment position. The deliver catheter may optionally include any ofthe aforementioned features. The removable stop may comprise first andsecond parts movable relative to each other.

The removable stop may optionally further comprise any one or anycombination of two or more of the following features (which are alloptional):

(i) The first and second parts may be arranged one part for bearing aremoval force, and the other part for bearing at least a portion of anopposite reaction to the removal force.

Such a stop is highly advantageous by reducing, to a large extent, thereaction to the removal force applied to the delivery device itself. Forexample, if using a traditional pull-out friction-fit pin, the surgeonhas to support the delivery device with one hand in order to support thereaction to the force applied with the other hand to pull-out the pin.Similarly, if using a screw threaded pin, the surgeon has to support thedelivery device with one hand to support the reaction to the unscrewingforce applied with the other hand to the pin. Unscrewing may also beinconvenient during an implantation procedure. In both cases, thereaction to the removal force is applied to the delivery device, andthere is a risk that minor movements of the delivery catheter handlewhen transmitted to the stent at the distal end, may have undesirableeffects. For example, the stent may be partly deployed and/or be inoperative contact with the anatomy. Minor movement can sometimes causeaccidental release of the stent or displace the stent out of a desiredimplantation position. In contrast, with the present aspect of theinvention, the two-part configuration of the removable stop can reducesignificantly the reaction to the removal force experienced by thedelivery catheter.

The first and second parts may be substantially coaxial about an axis ofthe stop, and slidable relative to each other along said axis.

One of the first and second parts of the stop may comprise a pull-outfriction-fit within an aperture of the delivery catheter handle, and theother part may comprise a pusher for pushing against the deliverydevice.

(ii) The first and second parts may have spaced apart portions that,when squeezed one towards the other, are configured to release the stopfrom the handle.

A further independent aspect of the invention provides a method of usinga delivery catheter for implanting a stented prosthetic aortic valve,the delivery catheter having a distal portion comprising: a tip memberand a sheath movable with respect to the tip member, the distal portioncarrying the prosthetic aortic valve constrained by the sheath, thesheath having a closed position in which the sheath abuts the tipmember; the method comprising:

-   (a) advancing the distal portion within a patient's anatomy towards    the implantation site;-   (b) subsequently partly displacing the sheath with respect to the    tip member such that the sheath is spaced from the tip member,    without deploying substantially the stent;-   (c) subsequently further advancing the distal portion with the    sheath spaced from the tip member, the spacing permitting the tip    member to flex with respect to the sheath member;-   (d) subsequently further displacing the sheath with respect to the    tip member in order to deploy the stent.

Such a method can address an issue of the sheath, when abutting the tipmember, potentially limiting the freedom of the tip member to flex. Bypartly displacing the sheath from the tip member, at least after havingpenetrated the heart and/or vascular system, the tip member can beallowed more freedom to flex at the expense of reduced support. This canbe used to assist advancement of the distal portion without deployingthe stent. For example, for a transapical delivery catheter, by partlydisplacing the sheath from the tip member after having penetrated theventricle (such as after having passed through an existing valve), thetip member can be allowed more freedom to flex. This can assistintroduction and/or advancement of the distal portion in the ascendingaorta and/or in the aortic arch, especially in cases where a person'sindividual anatomy may make such advancement difficult.

According to some embodiments, a delivery catheter for a stent isprovided wherein the delivery catheter comprises a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,the handle further comprising an indicator rotatable about thelongitudinal axis of the catheter, the indicator being positionable toindicate a rotational orientation of a stent with respect to the handle.The delivery catheter of some embodiments may comprise an indicator thatis manually settable. The stent may be a valve stent comprising a valvehaving valve leaflets and associated peripheral commissures, and whereinthe indicator comprises indicia for indicating the rotationalorientation of at least one of the commissures.

According to some embodiments, a delivery catheter for a stent isprovided wherein the delivery catheter comprises a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,wherein the handle comprises a bulbous portion intermediate distal andproximal ends of the handle, the bulbous portion providing a tactilepositioning guide for an operator's hand.

The bulbous portion may be one or more selected from: (i) rounded; (ii)frusto-spherical; (iii) distinct from the actuator. The bulbous portionmay have one or more dimensions selected from: (i) a radial heightcompared to at least one adjacent surface of at least 5 mm; (ii) anaxial extent of at least 20 mm; (iii) a radius of curvature of at least15 mm; (iv) a radius of curvature not greater than 60 mm.

According to some embodiments, a delivery catheter for a stent isprovided wherein the delivery catheter comprises a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,the actuator comprising a manual rotary control arranged such as to movethe sheath in the distal and/or proximal direction(s) along an operativerange of movement in response to rotation of the rotary control throughthree turns or less around the longitudinal axis of the catheter. Thedelivery catheter may further comprise a friction member forfrictionally resisting rotation of the rotary control.

According to some embodiments, a delivery catheter for a stent isprovided wherein the delivery catheter comprises a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,the actuator comprising a manual rotary control rotatable around thelongitudinal axis of the catheter and arranged such as to move thesheath in the distal and/or proximal direction(s), the rotary controlhaving a longitudinal length of at least 4 cm. The rotary control may beelongate in the direction of the longitudinal axis of the

According to some embodiments, a delivery catheter for a stent isprovided wherein the delivery catheter comprises a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,the actuator comprising a manual rotary control associated with ahelical thread than causes linear translation of the rotary controlrelative to the handle as the rotary control is turned, the handlefurther comprising indicia positioned so as to be progressively exposedor covered by the rotary control according to the linear position of therotary control, the indicia indicating an extent of displacement of thesheath at the proximal portion. The rotary control may be configuredsuch that the linear translation of the rotary control is the samelinear translation as the sheath.

According to some embodiments, an assembly is provided comprising aself-expanding stent-valve for replacing an aortic valve, and a deliverycatheter of the present invention. The stent may comprise first andsecond portions configured for engagement, in use, with opposite sidesof a native aortic valve annulus. The delivery catheter may comprise adistal end and a proximal end, the distal end including a stentattachment region adapted to receive the stent, the catheter furthercomprising a handle at its proximal end and at least one sheath for atleast partially circumferentially covering said stent such as to retainit in a collapsed configuration, the sheath being coupled at itsproximal end to an actuator located on said handle for actuatingmovement of the sheath, the actuator comprising a manual rotary control,and the handle further comprising indicia for indicating sheathdisplacement with respect to a first step for deploying the first stentportion and a second step for deploying the second stent portion.

According to some embodiments, a delivery catheter for a stent isprovided where the delivery catheter comprises a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,wherein a stem portion of the delivery catheter extending between saiddistal and proximal portions has a flexure characteristic such that, inorder to produce flexure displacement of 10 mm using a three-pointbending test, the applied force is between 2.5 and 7.5 N (inclusiverange). The stem portion of the delivery catheter may include a tubemember and a sheath member around the tube member.

According to some embodiments, a delivery catheter for a stent isprovided wherein the delivery catheter comprising a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,the delivery catheter further comprising a removable stop forobstructing actuator displacement beyond a certain position, theremovable stop comprising first and second parts movable relative to oneanother, the first and second parts being arranged one part for bearinga removal force, and the other part for bearing at least a portion of anopposite reaction to the removal force.

According to some embodiments, a delivery catheter for a stent isprovided comprising a distal end and a proximal end, the distal endincluding a stent attachment region adapted to receive a stent, thecatheter further comprising a handle at its proximal end and at leastone sheath for at least partially circumferentially covering said stentsuch as to retain it in a collapsed configuration, the sheath beingcoupled at its proximal end to an actuator located on said handle foractuating movement of the sheath, the delivery catheter furthercomprising a removable stop for obstructing actuator displacement beyonda certain position, the removable stop comprising first and second partsmovable relative to one another and having spaced apart portions that,when squeezed one towards the other, are configured to release the stopfrom the handle.

According to some embodiments, a delivery catheter for delivery of avalve is provided comprising a distal end and a proximal end, saiddistal end including a stent attachment region adapted to receive astent, preferably of the self-expanding type; said proximal endcomprising a handle; and at least one sheath which may at leastpartially circumferentially cover said stent such as to retain saidstent in a collapsed configuration, said sheath being coupled at itsproximal end to actuation means located on said handle, characterized inthat said actuation means consists of a single rotary handle partarranged such as to move said sheath in the distal and the proximaldirection.

According to some embodiments, a delivery catheter for delivery of avalve stent is provided comprising a distal end and a proximal end, saiddistal end including a stent attachment region adapted to receive astent, preferably of the self-expanding type; said proximal endcomprising a handle portion; and at least one sheath which may at leastpartially circumferentially cover said stent such as to retain saidstent in a collapsed configuration, characterized in that said deliverycatheter further comprises gear means providing for at least twodifferent transmission ratios between the movement of actuation meansand the movement of the sheath depending on the position of the distalend of the sheath along said stent.

According to some embodiments, a delivery catheter for delivery of avalve stent is provided comprising a distal end and a proximal end, saiddistal end including a stent attachment region adapted to receive astent, preferably of the self-expanding type; said proximal endcomprising a handle portion; and at least one sheath which may at leastpartially circumferentially cover said stent such as to retain saidstent in a collapsed configuration, said sheath being coupleable at itsproximal end to actuation means located on said handle portion such asto be moved along said stent, characterized in that said catheterfurther comprises feedback means and/or braking means, preferablytactile feedback means, to indicate when the distal end of the sheathhas reached a defined position on the stent during proximal and/ordistal movement of said sheath along said stent and/or to cause abraking effect once the distal end of the sheath moves beyond a definedposition along the stent.

According to some embodiments, a method is provided for using a deliverycatheter for implanting a stented prosthetic aortic valve, the deliverycatheter having a distal portion comprising: a tip member and a sheathmovable with respect to the tip member, the distal portion carrying theprosthetic aortic valve constrained by the sheath, the sheath having aclosed position in which the sheath abuts the tip member; the methodcomprising: advancing the distal portion within a patient's anatomytowards the implantation site; subsequently partly displacing the sheathwith respect to the tip member such that the sheath is spaced from thetip member, without deploying substantially the stent; subsequentlyfurther advancing the distal portion with the sheath spaced from the tipmember, the spacing permitting the tip member to flex with respect tothe sheath member; and subsequently further displacing the sheath withrespect to the tip member in order to deploy the stent. The step ofadvancing may comprise advancing the distal portion along a transapicalpath. The step of subsequently partly displacing the sheath with respectto the tip member such that the sheath is spaced from the tip member,without deploying substantially the stent may be carried out afterpenetrating a ventricle wall of the heart.

Further advantages and characteristics of the present invention aredescribed in the following description of examples and figures. TheApplicant claims protection for any novel feature or idea describedherein and/or illustrated in the drawings whether or not emphasis hasbeen placed thereon.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the present invention, reference is madeto the following description, taken in conjunction with the accompanyingdrawings, in which like reference characters refer to like partsthroughout.

FIG. 1 is a schematic side view of a first embodiment of deliverycatheter, with selected portions shown in cross-section.

FIG. 2 is a schematic section illustrating the proximal (handle) end ofthe delivery catheter of the first embodiment.

FIG. 3 is a schematic perspective view from above the proximal end(without the sheath represented).

FIG. 4 is a schematic perspective view from below the proximal end(without the sheath represented).

FIG. 5 is a schematic section showing a modified form of a handle usablewith the first embodiment.

FIG. 6 is a schematic section illustrating a three-point bending testfor the stem of the delivery catheter.

FIG. 7 is a schematic section illustrating one example of a distal endof the delivery catheter for the first embodiment.

FIG. 8 is a schematic section illustrating another example of a distalend of the delivery catheter for the first embodiment.

FIG. 9 is a schematic section illustrating a stage of partial opening ofa distal end of a delivery catheter.

FIG. 10 is a schematic plan view illustrating indicia on the handle ofthe proximal end of a delivery catheter.

FIG. 11 is a schematic section illustrating in detail a removable stop.

FIG. 12 is a schematic side view of a cylindrical threaded element ofone example.

FIG. 13 is a schematic side view of a cylindrical threaded element of afurther example.

FIG. 14 is a schematic side view of an exemplary stent valve optionallyused in connection with a delivery catheter according to the presentinvention.

FIG. 15 is a schematic section illustrating a second embodiment of adelivery catheter according to the invention.

DETAILED DESCRIPTION

In the following non-limiting detailed description, the same referencenumerals are used to denote equivalent or similar features whereappropriate. Further, reference is made to the accompanying drawingswhich form a part hereof, and in which is shown by way of illustration aspecific embodiment in which the invention may be practiced. It is to beunderstood that other embodiments may be utilized and structural changesmay be made without departing from the scope of the present invention.

FIGS. 1-14 illustrate a first embodiment of delivery catheter (alsoreferred to as exemplary delivery device 1) for implanting a stent(e.g., valve stent or stent-valve) 15. The delivery catheter 1 comprisesa proximal portion 1 a to be held by an operator, a distal portion 1 bfor insertion into the body, and a stem or barrel portion 1 c extendingbetween the proximal and distal portions.

A sheath 2 may extend from the proximal portion 1 a to the distalportion 1 b where it may cover at least partly a stent 15 accommodatedat a stent receiving portion 30, and arranged on tube member 3. Tubemember 3 may further comprise a lumen adapted for the insertion of aguide wire 29. The tube member 3 may extend through a handle 4 at theproximal portion 1 a. The handle 4 may comprise an actuator forcontrolling and/or driving linear translation of the sheath 2 in theproximal and/or distal direction(s). Translation of the sheath in e.g.,the proximal direction may uncover the stent to deploy or allowdeployment of the illustrated form, the actuator comprises a manuallyoperable rotary control (also referred to as a rotary handle or rotaryhandle member) 5.

Two examples of the proximal portion 1 a are illustrated in FIGS. 1-5,and have similar features as follows. The handle 4 may comprise acylindrical interior lumen into which the sheath 2 may be received. Aconnection member 13 may be coupled to the proximal end of the sheath 2.Optionally, the connection member 13 may comprise a valve 11, whichserves as inlet for a physiological saline solution used to flush thedistal end of the catheter delivery device 1. A rotary member 12 may bearranged proximally to the connection member 13, e.g. to avoid thephysiological saline solution to flow further towards the proximal endof the handle 4 and to rotationally support the various elements. Asliding member 10 may be arranged between rotary member 12 and athreaded cylindrical element 6. A removable stop 9 may be arranged onthe handle 4, e.g. removably received in an aperture 32. The stop 9 mayfunction to prevent proximal movement of the sheath beyond a certainpoint, corresponding to partial release and/or deployment of the stent15 without complete release and deployment. The stop 9 can engage thesliding element 10 to prevent the proximal movement of said element 10,and of the sheath 2, beyond said certain point. Only after removing thestop 9 the sheath 2 may be completely removed from the stent by movingthe sheath to a most proximal position. Further, a fixation element 14may be arranged in handle 4. The fixation element 14 may serve tostabilise the tube 3 against longitudinal movement with respect to thehandle 4. Fixation element 14 may engage a channel (for example definedby a pulley profile) associated with the tube 3.

The catheter delivery device 1 may further comprise gear means. The gearmeans include: a cylindrical threaded element 6 having a thread 7; and apin 8. The cylindrical threaded element 6 is coupled to the rotaryhandle (rotary control) acting as the actuator. The pin 8 is fixed withrespect to the handle 4, and the pin 8 is engaged into thread 7. Uponrotation of the actuator 5 the cylindrical threaded element 6 will alsoturn. As pin 8 is engaged into thread 7, the rotation of the element 6will result in a movement of the element 6 either in the proximal or inthe distal direction, depending on which way actuator 5 is turned. Asthe cylindrical threaded element 6 is coupled via sliding element 10,rotary element 12 and connection member 13 to the sheath 2, thetranslational movement of the cylindrical threaded element 6 will betransmitted to sheath 2.

The rotary handle 5 may be elongate in shape. The axial length may belonger than the diameter, for example, twice as large, or more. Therotary control may comprise an axial length of between about 3 cm toabout 15 cm, 20 cm or 30 cm, including at least 3 cm, or at least 4 cm,or at least 5 cm, or at least 6 cm, or at least 7 cm, or at least 8 cm,or at least 9 cm, or at least 10 cm. Such sizes can facilitate intuitivegripping in the hand, for example, cupping the rotary control with thefingers and/or palm. The outer shape of the rotary control may begenerally cylindrical and/or generally drum-like.

The tube 3 is optionally fitted at its proximal end with a luer valve46. The rotary handle 5 may include a socket or recess foraccommodating, at least partly, the shape of the luer valve 46 when therotary handle 5 is screwed or translated proximally. (Such accommodationis illustrated schematically in FIG. 2 although for the purposes ofspace in the drawing the rotary handle 5 is shown screwed towards thedistal portion 1 b).

The outer profile of the handle 4 may be generally cylindrical,optionally with one or more finger grips or recesses. Additionally oralternatively, the outer profile may include at least one bulbousportion 31, e.g. partly spherical in shape. Such a portion 31 may allowmore positive positioning of the handle in the hand according toindividual preferences.

The bulbous 31 portion may have a radial height, compared to at leastone adjacent surface of the handle, of between about 3 mm to about 10mm, 15 mm or 30 mm, including at least 5 mm, at least 6 mm, at least 7mm, or at least 8 mm. The bulbous portion 31 may have an axial extent ofany of between about 15 mm to about 40 mm, including at least 20 mm; atleast 25 mm; at least 30 mm. Additionally or alternatively to any of theabove, the bulbous portion 31 may have an axial extent of: not greaterthan 40 mm; not greater than 30 mm; not greater than 35 mm.

The bulbous portion 31 may have a frusto-spherical shape. The bulbousportion 31 may have a radius of curvature of any of between about 10 mmto about 40 mm, 50 mm or 60 mm, including at least 15 mm; at least 20mm; at least 23 mm. Additionally or alternatively to any of the above,the radius of curvature may optionally be: not greater than 60 mm; notgreater than 50 mm; not greater than 40 mm; not greater than 30 mm; notgreater than 25 mm; not greater than 23 mm.

Such arrangements of bulbous portion 31 can provide a highly intuitiveand versatile tactile positioning guide for the handle. The guide mayfit snugly in the palm of the hand, and/or be cupped comfortably by thefingers. The guide may also provide a suitable surface for gripping withthe fingers to apply axial force to the handle. The guide may alsoprovide substantially the same feel to the operator whatever therotational orientation of the handle 4 around the catheter axis.

FIGS. 7 and 8 show two examples of the distal portion 1 b of thecatheter delivery device. The examples are similar and differ only interms of the nature of the sheath 2. In both examples, the sheath 2comprises a constraining portion 2 a for covering a stent at the stentreceiving portion 30. The constraining portion 2 a may be an integralextension of the sheath 2, or it may be a reinforced sheath part bondedor otherwise permanently attached to the sheath 2. In the illustratedform, the constraining portion 2 a has substantially the same outerdiameter as the sheath 2 (at least no difference larger than 10%, ormore preferably no larger than 5%). Such constant size may facilitatesealing against blood leakage where the catheter penetrates the wall ofa blood vessel or the heart wall, even when no introducer is used. Forexample, a good seal may be achieved by advancing the distal portion 1 bthrough an undersized aperture in the ventricle wall. The elasticity ofthe ventricle wall permits passage of the distal portion 1 b through theundersized aperture, while tightly engaging the outer surface.

The stent 15 may be coupled to the tube member 3 by coupling means (alsoreferred to as a stent holder) 16, for preventing axial movement of thestent until the moment of full release and/or full deployment. The tubemember 3 may itself be reinforced over at least a part of its length bya dual wall structure (e.g., one tube nested within another, and coupledto function as a single unit). As evident at 3 a, the dual wallstructure may terminate distally of the coupling means 16. At the mostdistal tip, the catheter delivery device 1 may comprise a tip element20, for example having a conical from. The tip element 20 may allow foran easy insertion of the delivery catheter.

In the form illustrated in FIG. 7, the sheath 2 comprises (in the stemportion 1 c of the delivery catheter) an outer tube and an annularspacer member 2 c disposed between the outer tube 2 and the tube member3. The annular spacer member 2 c may be segmented and may serve toprevent kinking of the outer tube 2 b. The outer tube 2 b may be coupledto the constraining portion 2 a by means of an intermediate bridge 2 b.The bridge 2 b may optionally form part of, or be coupled to, theannular spacer member 2 c.

In the form illustrated in FIG. 8, the sheath 2 comprises a thicker walltube without an annular spacer member. The thicker wall tube resistskinking.

Referring to FIG. 6, in some embodiments the stem portion 1 c may have aflexure characteristic such that, in order to produce flexuredisplacement of 10 mm using a three-point bending test, the appliedforce may be (i) between 2.5 and 3.5 N (inclusive range), or (ii)between about 6.0 and 7.5N (inclusive range), or (iii) generally betweenabout 2.5 and 7.7N (inclusive range). The three-point bending test maycomprise supporting the stem portion at two spaced apart positions 33,and observing the degree of bending displacement when a force isapplied, in a diametrically opposed direction to the supports, at aposition 34 midway between the spaced apart support positions. Thespacing between the support positions may be about 16 to about 20 timesthe outer diameter of the stem. The flexure displacement may be measuredas a displacement with respect to a condition of the stem 1 b when noforce is applied (e.g. substantially straight, or with only slightflexure). The applied force range (i) may optionally be associated witha spacing of 20 times the outer diameter. The applied force range (ii)may optionally be associated with a spacing of 160 mm and/or an outerdiameter of 9.8 mm (+−0.5 mm) and/or a spacing that is about 16 timesthe outer diameter.

Such a flexure characteristic may be advantageous in meeting theconflicting desirata of flexibility and support. Especially in the caseof a transapical approach, the delivery catheter has to providesufficient support to be able to advance the distal end through arelatively tight access aperture in the ventricle wall. It is desirablethat the aperture in the ventricle be as small as possible, to reducerisk of interference with the distribution of natural electrical pulsesessential to healthy heart operation, and/or reduce the invasiveness ofthe procedure on the heart tissue, and/or facilitate easier closingafter the procedure to restore the integrity of the ventricle wall,and/or facilitate the patient's recovery after the procedure. It isdesirable to create the access aperture undersized, and rely on theelasticity of the heart muscle tissue to allow the aperture to expandelastically to accommodate passage of the delivery cathetertherethrough. Such a tight fit can also provide a self-seal againstblood leakage, the procedure being carried out while the heart remainsbeating to pump blood around the circulatory system. The deliverycatheter also has to be flexible to accommodate a non-straight deliverypath through the heart and the existing valve. Different surgeons havedifferent preferences for the entry path through the anatomy to theheart. The flexure characteristic defined herein can provide asurprisingly good balance between the support and flexibility.

Referring to FIGS. 7-9, in some embodiments, a method is used forselectively enhancing flexibility of the distal portion 1 b. As can beseen in FIGS. 7 and 8, in the closed position of the sheath 2, thesheath 2 may abut a confronting surface of the tip element 20. Suchabutment may support stably the tip element 20 when the tip 20 isadvanced through an undersized aperture in the ventricle wall. Onceinside the heart, and/or after having advanced at least partly thoughthe valve to be replaced, it may be desirable to allow the tip element20 more freedom to flex. Referring to FIG. 9, in the some embodiments,this is achieved by displacing the sheath 2 partly (as indicated byarrow A), so that it no longer abuts the tip element 20 (as indicated atB), but is not sufficiently displaced to allow substantial deployment ofthe stent 15. Displacing the sheath 2 away from the tip element 20removes the direct support, thereby permitting the tip 20 greaterfreedom to flex (indicating by arrow C). Following such partial orlimited displacement, the distal portion 1 b may be further advancedinto the heart and/or ascending aorta, while benefitting from theenhanced flexibility of the tip, until the distal portion 1 b arrives ata desired position for deployment of the stent 15. Thereafter, thesheath 2 is displaced further in the direction of arrow A to release thestent 15.

In some embodiments, the handle 4 carries an indicator 35 forindicating, to the operator viewing the proximal portion 1 a of thecatheter, the rotational orientation of the stent 15 carried at thedistal portion 1 b. Depending on the design of stent 15, it may bedesirable to implant the stent with a certain rotational orientationwith respect to the local anatomy. The stent 15 may have anon-predetermined, or variable, rotational orientation with respect tothe stent holder 16 and/or to the handle 4. However, although theorientation may be non-predetermined, it may remain constant once thestent 15 has been loaded into the stent containing region 30 andconstrained by the sheath 2. Once loaded, the operator can set theindicator 35 to indicate the orientation of the stent 15 at loading. Theindicator 35 enables the operator to known the orientation of the stent,even when the distal portion 1 b is hidden with the anatomy. Theprocedure may be carried out using medical imaging from which the stentorientation may also be derivable, but the presence of an indicationdirectly on the handle 4 provides the operator with additionalinformation to avoid any ambiguitiy.

In the illustrated forms, the indicator 35 comprises a ring or collarrotatable around the axis of the handle and/or delivery catheter. Theindicator 35 is manually settable by manual rotation. A friction member36 (e.g. an O-ring of elastomeric material) frictionally resistsrotation of the indicator 35, so that it is unlikely to slip out of theset position in use. In some embodiments, the indicator 35 carries orcomprises visual indicia 37. For example, the indicia 37 may be printedon the indicator 35, or comprise distinct elements (e.g. as in FIG. 4).

In some embodiments, the stent 15 comprises plural commissuresassociated with the shape of the stent and/or the valve. The indicator35 may bear plural indicia 37, one for each commissure. By way ofexample only, FIG. 14 shows one example of a stent 15 optionally used inconnection with a catheter delivery device 1 of the present invention.The stent 15 has a distal end 26, a proximal end 27 and comprisesstabilization arches 21, commissural posts 22, upper anchoring crown 23,lower anchoring crown 24 as well as attachment elements 25. Thestabilization arches 21 serve to stabilize the stent 15 in a bloodvessel, preferably the aorta, during deployment. Typically, threeleaflets of a replacement heart valve are attached to commissural posts22. The upper anchoring crown 23 serves to attach the stent 15 in theaortic side of a heart valve, while the lower anchoring crown serves toattach the stent 15 on the ventricular side of the heart valve.Attachment means 25 enable the removable attachment of the stent 15 tothe stent holder 16 of the catheter delivery device 1. The illustratedstent 15 has three commissures, and the indicia 37 may comprise threerespective indications.

In some embodiments, the delivery catheter 1 comprises feedback meansfor providing an indication to the operator of: (i) the sheath position(e.g. degree to the which the sheath is displaced open); and/or (ii)release state of the stent 15; and/or (iii) when the sheath reaches apredetermined release position associated with a release phase of thestent.

In some embodiments, the feedback means comprises a visual indication 38on the handle. Referring to FIG. 10, the indicator 38 comprises indiciaon a portion of the surface of the handle 4 that is selectively coveredor exposed, depending on the position of the rotary control 5. Thethreaded connection between the rotary control 5 and the handle 4results in the rotary control 5 translating linearly (as indicated byarrow D) as the rotary control 5 is turned. The rotary control 4translates linearly with the sheath 2. The linear position of the rotarycontrol 5 thus provides a representation of the linear position of thesheath 2. The indicator 38 is provided at a position on the handle 4such that the indicator 38 is progressively exposed by the lineartranslation of the rotary control 5. The indicator 38 may for example,comprise a scale indicating the extent to which the sheath 2 is open atthe distal portion 1 b (for example, represented by a triangular form,the spacing between the two long sides indicating the extent to whichthe sheath is open). Additionally or alternatively, the indicator 38 maycomprise one or more marks 39 indicating when a certain release positionof the sheath 2 has been achieved. For example, if the stent 15 has theform illustrated in FIG. 14 and described above, it may be intended forrelease in plural steps or phases S1 and S2+ (which may be S2+S3 in FIG.14). A first step S1 corresponds to the release of the stabilizationarches 21 and, optionally, the upper crown 23. A second step (S2+)includes release of the lower crown 24 and, optionally, the attachmentelements 25. The indication marks 39 enable the operator to see when therespective release point of each step or phase is expected to occur, andto control the delivery catheter 1 accordingly.

The indications 38 and/or 39 may be repeated at plural positions aroundthe circumference of the handle 4, so that at least one indication 38/39may always be in view irrespective of the rotational orientation of thehandle 4. Additionally or alternatively, the indications may becircumferentially continuous (e.g., as represented by thecircumferential broken lines at 39).

As mentioned previously, the removable stop 9 may also provide tactilefeedback to the operator about when the sheath reaches the end of thefirst step S1. The removable stop 9 may be configured to obstructfurther linear translation of the sheath 2 once the end of the firststep S1 has been reached.

In a simple form (e.g. as in FIG. 5), the removable stop 9 may consistof a pin having a friction member (e.g. an O-ring of elastomericmaterial) at its end insertable into the aperture 32. In a more enhancedform (FIGS. 1-4 and 11), the removable stop 9 may consist of first andsecond parts 40 and 41 that are displaceable relative to each other. Thefirst and second parts 40 and 41 may be arranged one part for bearing aremoval force, and the other part for bearing at least a portion of anopposite reaction to the removal force. Such a stop is highlyadvantageous by reducing, to a large extent, the reaction to the removalforce applied to the delivery device itself. For example, if using apull-out friction-fit pin as in FIG. 5, the reaction force is applied tothe delivery catheter, and the operator has to support the deliverycatheter with one hand in order to support the reaction to the forceapplied with the other hand to pull-out the pin. However, minor movementor perturbation of the delivery catheter can sometimes cause accidentalrelease of the stent or displace the stent out of a desired implantationposition. In contrast, a two-part configuration 40, 41 of the removablestop 9 can reduce significantly the reaction to the removal forceexperienced by the delivery catheter. The first and second parts 40 and41 may be substantially coaxial about an axis of the stop, and slidablerelative to each other along said axis. One part 40 may comprise apull-out friction-fit within the aperture 32 of the handle 4, and theother part 41 may comprise a pusher for pushing against the deliverydevice. The first part 40 may carry a friction member 40 a (similar tothat described above). The second part 41 may have a pusher tip 41 a.The first and second parts 41 may have spaced apart manually engageableportions that, when squeezed one towards the other (as indicated by thearrows 42 in FIG. 9) are configured to release the stop 9 from thehandle 4.

FIGS. 12 and 13 show different examples of the cylindrical threadedelement 6 usable in the first embodiment. The example of FIG. 12 isshown used in the handle of FIG. 2, and the example of FIG. 13 is shownused in the handle of FIG. 5, but this selection is merely for the sakeof illustration, and either example of element 6 may selected for eachhandle as desired.

Both examples of cylindrical threaded elements 6 comprise an internallumen 18 through which tube member 3 and/or a guide wire may beinserted. Connection element 17 allows to connect the cylindricalthreaded element 6 to an actuation means such as the rotary handle 5. Anadditional axle member 19 allows to rotationally connect member 6 tofurther elements and/or to the handle 4. The cylindrical threadedelement 6 comprises thread 7. The thread 7 may have any suitablecross-section form, such as rectangular (as in FIG. 13) or rectangularwith an additional guide-groove 43 (FIG. 12) for co-operating with a tipof the pin 8.

The element 6 is configured to drive linear translation of the sheath 2between operative closed and open positions, over a full operative rangeof linear movement, by three turns or less about the catheter axis. InFIG. 12, the full operative range of movement is achieved by two turnsor less. In either case, a friction member 45 (FIG. 2) may optionally beprovided to resist self-rotation that might otherwise occur when using arelatively coarse thread 7 to achieve such translation for fewrotational turns. The friction member 45 may be positioned betweenconfronting surfaces of the rotary control 5 and the handle 4. Forexample, the friction member 45 may be mounted in a groove on the outersurface of the handle 4 for bearing against an inner surface of therotary control 5. The friction member 45 may comprise an O-ring ofelastomeric material. Such an arrangement can provide reliable andreproducible control over the amount of friction between the handle 4and the rotary control 5, and facilitate simple construction.

In the example of FIG. 12, thread 7 has a substantially uniform threadpitch. Such a thread 7 produces uniform gearing between the rotarycontrol 5 and the sheath 2 over the entire range of movement. In thealternative example of FIG. 13, thread 7 has three sections withdifferent thread pitches H1, H2 and H3. The different thread pitches H1,H2 and H3 allow having different gearing ratios between the movement ofthe actuation means 5 and the movement of the sheath 3. Alternatively,the member 6 may also comprise further sections with yet differentthread pitches. For example, further intermediate sections may define aprogressive incremental change in thread pitch (e.g., between H1 and H2)in order to avoid large step changes or discontinuities in the threadsmoothness. The different thread pitches may be in the range of about 5mm to about 50 mm, including , for example, about 10 mm to about 40 mm,about 15 mm to about 30 mm , or about 5 mm to about 35 mm. Table 1 showsan example of different thread pitches which may be used for the thread7 of the cylindrical threaded element 6:

TABLE 1 Thread Thread pitch section [mm] H1 30 H2 10 H3 15

Referring to the different thread pitches H1, H2 and H3 of thread 7 asshown in FIG. 13, and the stent example shown in FIG. 14, the threadpitch H1 is configured such as to provide a first transmission or gearratio when moving the distal end of the sheath 3 along the first portionS1 of the stent 15. Accordingly, the thread pitch H2 is arranged such asto provide a different second transmission or gear ratio, such as alower second transmission or gear ratio when the distal end of thesheath 2 moves along portion S2 of the stent 15. Finally, thread pitchH3 may be adapted such as to provide yet a different third transmissionor gear ratio when the distal end of the sheath 2 moves along theportion S3 of the stent 15. The diagrams (a) and (b) in FIG. 4illustrate two alternatives examples for the portions S1, S2 and S3; itwill be appreciated that other configurations are also possible.

FIG. 15 shows an alternative embodiment 1 of the catheter deliverydevice 1 according to the present invention. A stent attachment region28 is located at the distal end of the catheter device, holding thecatheter 15. At its most distal tip, the conical section 14 is arranged.The sheath 2 extends from the handle 4 located at the proximal end ofthe catheter device 1 to the distal end. As such, the sheath 2 may atleast partially or completely circumferentially cover the stent 15. Tubemember 3 extends along the entire length of the delivery device 1 andcomprises a guide wire 29. In this embodiment, the actuation means areconfigured as trigger element 5. The handle 4 comprises a pistol grip 31to enable a safe and easy handling of the catheter device by anoperator. The device 1 further comprises braking means 9 configured ascylindrical, optionally self turning, threaded element. The threadedelement may be analogous to the threaded element 6 as shown on FIG. 4.Said threaded element may optionally include a thread 7 with differentthread pitches, which applies a resistance to the actuation means 5having a braking effect. When the trigger 5 is pulled back, the slidingmember to which the sheath is attached abuts against an abutmentsurface. Upon further actuation of the trigger, the treatment element isrotated due to its self turning design. If the pitch becomes lower, theforce which has to be applied by the trigger becomes bigger or selfturning becomes impossible so that the movement is stopped.Alternatively, the thread pitch may be uniform, and the braking effect(increased) resistance is created by the sliding member to which thesheath is attached abutting the thread partway along the reciprocal runof the sliding member. For example, the sliding member may slide in aproximal direction freely or substantially “unbraked” over a firstmovement range to a predetermined position without contacting thethread; when the sliding member reaches the predetermined position, thesliding member abuts the thread, such that the braking effect is appliedfor the remainder of the range of proximal movement.

Definitions

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. Although methods and materialssimilar or equivalent to those described herein can be used in thepractice or testing of the present invention, suitable methods andmaterials are described below. All publications, patent applications,patents, and other references mentioned herein are incorporated byreference in their entirety. In the case of conflict, the presentspecification, including definitions, will control. In addition, thematerials, methods, and examples are illustrative only not intended tobe limiting. Other features and advantages of the invention will beapparent from the following detailed description and claims.

For the purposes of promoting an understanding of the embodimentsdescribed herein, reference will be made to preferred embodiments andspecific language will be used to describe the same. The terminologyused herein is for the purpose of describing particular embodimentsonly, and is not intended to limit the scope of the present invention.As used throughout this disclosure, the singular forms “a,” “an,” and“the” include plural reference unless the context clearly dictatesotherwise. Thus, for example, a reference to “a device” includes aplurality of such devices, as well as a single device.

Throughout this application, the term “about” is used to indicate that avalue includes the standard deviation of error for the device or methodbeing employed to determine the value.

Reference to numeric ranges throughout this specification encompassesall numbers falling within the disclosed ranges. Thus, for example, therecitation of the range of about 1% to about 5% includes 1%, 2%, 3%, 4%,and 5%, as well as, for example, 2.3%, 3.9%, 4.5%, etc. In someinstances in the specification the term “inclusive” is used to reiteratethis point.

The use of the term “or” in the claims is used to mean “and/or” unlessexplicitly indicated to refer to alternatives only or the alternativesare mutually exclusive, although the disclosure supports a definitionthat refers to only alternatives and “and/or.”

As used in this specification and claim(s), the words “comprising” (andany form of comprising, such as “comprise” and “comprises”), “having”(and any form of having, such as “have” and “has”), “including” (and anyform of including, such as “includes” and “include”) or “containing”(and any form of containing, such as “contains” and “contain”) areinclusive or open-ended and do not exclude additional, unrecitedelements or method steps.

1.-23. (canceled)
 24. A delivery catheter for delivery of a valve stent,comprising a distal end and a proximal end, said distal end including astent attachment region adapted to receive a stent, preferably of theself-expanding type; said proximal end comprising a handle portion; andat least one sheath configured to at least partially circumferentiallycover said stent such as to retain said stent in a collapsedconfiguration, said sheath being coupleable at its proximal end to anactuator located on said handle portion such as to be moved along saidstent at least one of feedback means and braking means to indicate whenthe distal end of the sheath has reached a defined position on the stentduring proximal and/or distal movement of said sheath along said stentand/or to cause a braking effect once the distal end of the sheath movesbeyond a defined position along the stent.
 25. A delivery catheteraccording to claim 24, wherein the actuator comprises a manual rotarycontrol associated with a helical thread than causes linear translationof the rotary control relative to the handle as the rotary control isturned, the handle further comprising indicia positioned so as to beprogressively exposed or covered by the rotary control according to thelinear position of the rotary control, the indicia indicating an extentof displacement of the sheath at the proximal portion.
 26. The deliverycatheter according to claim 25, wherein the rotary control is configuredsuch that the linear translation of the rotary control is the samelinear translation as the sheath.
 27. A delivery catheter according toclaim 24, wherein the valve stent comprises first and second portionsconfigured for engagement, in use, with opposite sides of a nativeaortic valve annulus; and wherein the actuator comprises a manual rotarycontrol, and the handle further comprising indicia for indicating sheathdisplacement with respect to a first step for deploying the first stentportion and a second step for deploying the second stent portion.
 28. Adelivery catheter according to claim 24, wherein the actuator comprisesa manual rotary control arranged such as to move the sheath in thedistal and/or proximal direction(s) along an operative range of movementin response to rotation of the rotary control through about three turnsor less around the longitudinal axis of the catheter.
 29. The deliverycatheter according to claim 28, further comprising a friction member forfrictionally resisting rotation of the rotary control.
 30. A deliverycatheter according to claim 24, wherein the actuator comprises a manualrotary control rotatable around the longitudinal axis of the catheterand arranged such as to move the sheath in the distal and/or proximaldirection(s), the rotary control having a longitudinal length of atleast 4 cm.
 31. The delivery catheter of claim 30, wherein the rotarycontrol is elongate in the direction of the longitudinal axis of thecatheter.
 32. A delivery catheter according to claim 24, wherein a stemportion of the delivery catheter extending between said distal andproximal portions has a flexure characteristic such that, in order toproduce flexure displacement of about 10 mm using a three-point bendingtest, the applied force is between about 2.5 and about 7.5 N.
 33. Thecatheter according to claim 32, wherein in the stem portion, thedelivery catheter includes a tube member and a sheath member around thetube member.
 34. A delivery according to claim 24, wherein the handleportion further comprises an indicator rotatable about the longitudinalaxis of the catheter, the indicator being positionable to indicate arotational orientation of a stent with respect to the handle.
 35. Thedelivery catheter of claim 34, wherein the indicator is manuallysettable.
 36. The delivery catheter of claim 34, wherein valve stentcomprises a valve having valve leaflets and associated peripheralcommissures, and wherein the indicator comprises indicia for indicatingthe rotational orientation of at least one of the commissures.
 37. Adelivery catheter according to claim 24, wherein the handle portioncomprises a bulbous portion intermediate distal and proximal ends of thehandle portion, the bulbous portion providing a tactile positioningguide for an operators hand.
 38. The delivery catheter of claim 37,wherein the bulbous portion is one or more selected from: (i) rounded;(ii) frusto-spherical; (iii) distinct from the actuator.
 39. Thedelivery catheter of claim 37, wherein the bulbous portion has one ormore dimensions selected from: (i) a radial height compared to at leastone adjacent surface of at least 5 mm; (ii) an axial extent of at least20 mm; (iii) a radius of curvature of at least 15 mm; (iv) a radius ofcurvature not greater than 60 mm.
 40. A delivery catheter according toclaim 24, wherein said actuation means consists of a single rotaryhandle part arranged such as to move said sheath in the distal and theproximal direction.
 41. A delivery catheter according to claim 24,wherein said delivery catheter further comprises one or more gearsconfigured for at least two different transmission ratios between themovement of actuation means and the movement of the sheath depending onthe position of the distal end of the sheath along said stent.
 42. Adelivery catheter for a stent, optionally according to claim 24, thedelivery catheter comprising a distal end and a proximal end, the distalend including a stent attachment region adapted to receive a stent, thecatheter further comprising a handle at its proximal end and at leastone sheath for at least partially circumferentially covering said stentsuch as to retain it in a collapsed configuration, the sheath beingcoupled at its proximal end to an actuator located on said handle foractuating movement of the sheath, the delivery catheter furthercomprising a removable stop for obstructing actuator displacement beyonda certain position, the removable stop comprising first and second partsmovable relative to one another, the first and second parts beingarranged one part for bearing a removal force, and the other part forbearing at least a portion of an opposite reaction to the removal force.43. A delivery catheter for a stent comprising a distal end and aproximal end, the distal end including a stent attachment region adaptedto receive a stent, the catheter further comprising a handle at itsproximal end and at least one sheath configured for at least partiallycircumferentially covering said stent such as to retain it in acollapsed configuration, the sheath being coupled at its proximal end toan actuator located on said handle for actuating movement of the sheath,the delivery catheter further comprising a removable stop forobstructing actuator displacement beyond a certain position, theremovable stop comprising first and second parts movable relative to oneanother and having spaced apart portions that, when squeezed one towardsthe other, are configured to release the stop from the handle.